FIM-'AVII KXIIIKITION. 



881 





in with. As the shot breaks 

 the \\iiv a momentary interruption results, and 



n -park i- deport, ,! close beside tho lino marked 

 I iy tln< timing-fork. As the lirst screen is de- 

 prived of its place in the galvanic circuit, the 

 ! oomtt into play, transferring its duties, 

 \\ln-u it is broken, to the third, and soon, a 

 spark being dropped upon tho cylinder and 

 making its mark each time that a screen is 

 .-truck. It only remains to measure each in- 

 terval of tho shot's flight by the scale of time 

 i be-ide tho spark-marks on the cylinder, 

 and the retarding force of the atmosphere can 

 ily calculated. 



In Hashforth's instrument a piece of glazed 

 paper is stretched on the surface of the cylinder, 

 and against tho paper press lightly two little 

 with sharp points, one of them being 

 under the influence of a clock beating half-sec- 

 onds, the other governed by the rupture of tho 

 screens. As the cylinder revolves, the two 

 points advance and draw parallel helices side 

 l>y s 'de. At each beat of the clock its pointer 

 darts aside, interrupting for a moment the 

 regularity of the line. A similar action takes 

 place with the other pointer every time that a 

 MTceii is struck ; so he-re, again, we have a scale 

 of time and another of the shot's motion laid 

 down almost in contact. 



Both Bashforth's and Sclmltz's screens are al- 

 most exactly the same. Bashforth suspends 

 weights to slight threads, and so keeps down a 

 nuniher of springs. When the shot cuts a 

 thread its spring is released, and the sensitive 

 marker springs aside until the spring has struck 

 an upper brass plate in its recoil. Schultz has 

 springs, but ties them down with wires, one to 

 each spring; they act in precisely the same 

 manner. 



/:'/"! rii- J:'iiijr<ii-infj Machine. An ingenious 

 machine was exhibited in London, in 1862, for 

 \ ing designs upon printing rollers, by 

 means of a series of cutting points operated 

 upon by electro-magnetism. The design, from 

 which the engraving forms a repetition of 

 copies, is made from a metallic plate with a 

 IK m-conductive varnish or color, and is traced 

 over by a point of platinum, while the cylinder 

 which is to ho operated upon receives a slow 

 but uniform rotating movement. The platinum 

 tracer, in passing alternately over tho metallic 

 and the- non-conductive points in the design, 

 makes and breaks an electric current which 

 - through the metallic plate and the tracer 

 itself. The electric current acts upon the cut- 

 ting points of several engraving tools, which 

 are pressed against their work, or withdrawn 

 from it, according to the changes in the cur- 

 rent. The inventor, M. Gaiffo, has now carried 

 out the same idea in a more general form, and 

 exhibits inthc Exhibition an engraving machine 

 for copying designs, reducing them to different 

 -cales, .! ^graving them on copper plates 

 ready for printing in tho usual manner. The 

 original design is made upon a copper plate, by 

 preference on a much larger scale than the in- 



tended reduced designs. Tho copper [date ia 

 mounted on a frame in which i: a glow 



rotation round a hori/ontal spindh- 

 manner as the face plate of a lathe. The cop- 

 per plates upon which reduced copies are to be 

 produced are mounted cadi upon a similar spin- 

 dle and all geared together with tho original 

 plate, so as to give the same rate of rotation to 

 each. Opposite to the plate which carries the 

 original dc-ign is fixed a kind of slide-rest mov- 

 ing over a horizontal bed by means of a screw, so 

 as to give to the whole the exact appearance of 

 a miniature face lathe. This slide-rest carries 

 the platinum point for making and breaking 

 the electric contact, and tho bed upon which it 

 travels is continued in front of the several other 

 face plates which are to receive the engraving. 

 Opposite to each of the latter plates another 

 carriage is placed, and each of these carriages 

 is traversed by means of a screw-spindle which 

 forms the continuation of the screw, working 

 the slide opposite the original plate. The 

 screws, however, are cut with different pitches 

 for each different plate, so that the rotation of 

 the screw-spindle will produce a different 

 amount of traverse for each slide. The result 

 of this arrangement is a uniform rotating 

 movement for all plates and a sliding move- 

 ment for all carriages, which is proportioned to 

 their respective pitches of screws. Each of 

 the slides carries a diamond point mounted in 

 a delicate frame and pressed forward by a 

 spring. The spindle carrying the diamond is 

 connected to a small piece of iron which is 

 placed opposite a pair of electro-magnets, and 

 is attracted by them whenever a current passes 

 through their coils. The action of the magnets 

 thereby withdraws the diamond point from the 

 plate whenever electric contact is established. 

 During the time that the current is broken the 

 electro-magnet sets the diamond point free, and 

 the latter is pressed against, the plate by the 

 spring. As the original plate passes slowly in 

 front of the platinum point, the latter moving 

 horizontally at the same time, the line traced 

 upon the plate by the platinum point is a spiral 

 of very tine pitch, and a similar spiral, only of 

 still finer pitch, is traced by each diamond 

 point over its respective plate. The engravings 

 so produced can be made in considerable num- 

 bers simultaneously, and at the same time may 

 be made to different scales. 



Tho accuracy with which engravings are 

 copied by this machine has its equal only in 

 electrotyping ; with the advantage of allowing 

 of a reduction in size. 



Electricity applied to Stocking-Loom*. In two 

 of the circular looms of M. Berthelot & Co. ar- 

 rangements were introduced whereby the break- 

 ing of a thread would at once notiiy the fact to 

 the attendant, in the one case by ringinug an elec- 

 trical bell, in the other by stopping the machine. 



Radiguet and Lec&ne, of Paris, exhibit sev- 

 eral circular stocking-frames, in which by tho 

 aid of electricity the machine is .-topped when 

 a thread breaks, a lever in such event establish- 



